Effect of blade-row axial spacing on the stage performance of an axial supersonic through-flow fan

Rotor-stator interaction has a large impact on the performance of axial compressors. Previous studies have suggested that less blade-row axial spacing (delta(z)) of an axial flow compressor is associated with improved efficiency. However, these studies primarily focused on the subsonic-axial turbomachinery. The impact of delta(z) on the performance in an axial supersonic through-flow fan (STFF) stage remains unclear. This study explores the effect of axial spacing on the performance of an STFF stage using unsteady numerical simulations. The results show that both the total pressure ratio and adiabatic efficiency are reduced when axial spacing changes from delta(z) = 1.0 regardless of whether it increases or decreases. Notably, the maximum drop in total pressure ratio and efficiency occurs at delta z = 4.0 and delta z = 2.0, respectively. Furthermore, the study also reveals the loss production mechanisms which driving stage performance variations. When axial spacing drops from 1.0 to 0.5, the stage loss dominated by the wake-shock interaction loss is enhanced due to the stronger wake strength. When axial spacing rises from 1.0 to 2.0, however, the wake mixing loss plays a leading role in stage loss. Additionally, larger axial spacing further amplifies wake-shock interaction due to increased viscous dissipation.